Sperm Maturation & Assessment Flashcards
What changes does sperm undergo? (6 main changes)
- acquire motility
- proteome changes (protein contents)
- glycocalyx changes (sugars)
- migration of cytoplasmic droplet
- membrane lipid changes
- non-coding RNA changes
Post-testicular maturation: the epididymis: - Features of the caput epididymis sperm
- immotile
- infertile
- proximal cytoplasmic droplet: up towards head of the sperm
- proximal part= absorption of rete testis fluid
- distal head = secretion of epididymal fluid.
Corpus epididymis (middle of the epididymis) sperm features: (think of middle part of the process) including epididymis function in this section.
- motile kind of (after dilution and not great)
- maybe fertile (halfway)
- translocating cytoplasmic droplet → moving further away from head
- epididymis: secretion of fluid (proteins etc.) and extracellular vesicles
Cauda epididymis: sperm features in this section and what is the epididymis function in this region (fluid related etc.)
- sperm is motile
- fertile
- distal or no cytoplasmic droplet
- Epididymis: reabsorption of fluid and storage of sperm for ejaculation
Cauda (tail) epididymis: sperm features in this section and what is the epididymis function in this region (fluid related etc.)
- sperm is motile
- fertile
- distal or no cytoplasmic droplet
- Epididymis: reabsorption of fluid and storage of sperm for ejaculation (only in cauda)
Epididymal transit timing: time takes from caput-cauda of the epididymis is approximately:
- Why is it important to factor the epididymal transit timing in sperm production?
- approx 2 weeks between species
- important to factor this time in if calculating when to reassess semen quality after a disease/heat stress/trauma etc. → must wait spermatic cycle time AND epididymal transit time
Post epididymal maturation: what impacts the sperm storage in the cauda epididymis that prevents build up of sperm?
- ejaculation frequency
- regular voiding via the urine to avoid build up
After storage of sperm in epididymis, what then drives further maturation of sperm?
- seminal plasma
- the female tract
Assessment of sperm structure and function: what are the key assessment parameters?
- volume
- colour/consistency
- motility
- morphology
- concentration
What can we assess when looking at semen colour/consistency?
- Creamy coloured and thick
- clear and watery → won’t have as much sperm in there.
- colour: could indicate blood in ejaculate or really yellow = urine in ejaculate as well
Sperm motility: how can we assess sperm motility (2 main steps)
- Dilute semen using an osmotically appropriate medium (saline**) to see individual sperm
- create a wet prep and assess
- total motility(% sperm with movement)
- ***progressive motility (% sperm with strong FORWARD movement)
How do we assess sperm morphology (do we want them to be motile?)
what are the 3 sperm morphology results?
- we do not want sperm to be moving when assessing morphology- so fix the sperm to stop motility
- assess 100 sperm minimum for structural abnormality %
- Basic (% abnormal)
- intermediate (% head defects, tail defects etc.)
- advanced (% folded tail, % knobbed acrosome)
What are the 3 rules for semen handling
- Clean - dirt and dust will impact motility assessment and kill sperm
- warm - sperm are happy at 37degrees - cold temps lower motility and kill sperm
- dry - water is hypotonic and will kill sperm
Average volume of sperm in different species:
- species specific ejaculation volume
- e.g. bull 2-8mL, boar 100-500mL, stallion 20-80mL
Why would diluting sperm samples with sterile injection water be bad for testing motility?
- inappropriate dilution medium - sperm are hydrophobic meaning that water will kill sperm/severely impact motility
